Abstract

Evidence for global warming is inferred from spring advances in first-flowering in plants. The trend of average first-flowering times per year for the study group shows a significant advance of 2.4 days over a 30-year period. When 11 species that exhibit later first-flowering times are excluded from the data set, the remaining 89 show a significant advance of 4.5 days. Significant trends for earlier-flowering species range from -3.2 to -46 days, while those for later-flowering species range from +3.1 to +10.4 days. Advances of first-flowering in these 89 species are directly correlated with local increase in minimum temperature (Tmin).

Shetler SG andWiser SK (1987) First flowering dates for spring-blooming plants of the Washington, DC, area for the years 1970 to 1983. Proceedings of the Biological Society of Washington 100: 993-1017Google Scholar